Yellow fog inhibitor for photographic materials



Patented Apr. 15, .1941

UNiTED STATES 2,238,632 PATENT ,oFFioE YELLOW FOG INHIBITOR FOR PHDTQ- GRAPHIC MATERIALS Fritz Dersch and Newton Heimbach, Binghamton,

N. Y., assignors, by mesne assignments, to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing.s

11 Claims.

as grey fog and may be caused by premature exposure of the emulsion to light, by over-ripening of the emulsion during manufacture and handling, or by the normal aging of the emulsion over a. period of time. The second type of fog, and the one with which this application is concerned, is variously referred to as yellow fog, color fog, or dichroic fog. This yellow fog essentially comprises a colloidal deposit of silver, the color intensity and appearance of which are chiefly determined by the great degree of subdivision and minute particle size involved. This colloidal silver deposit is usually yellow and is most discernible in the lighter portions of a negative; The silver particles may, however, appear green? by reflected light and yellow or red by trans-.- mitted light, in which case the eifect is often spoken of as color fog or dichroic fog.

The occurrence of yellow fog may be traced to the particular emulsion involved or to one of" its constituents, or to some element in the preparation of the emulsion. Unfavorable conditions during the processing of the film may also cause such fog, Thus the use of nearly exhausted developing or fixing solutions, or the use of a developer which contains small amounts of fixing solution or an excess of silver halide solvent such as sulfite will tend to favortheformation of these minute colloidal silver particles. Inthe handling of X-ray films in particular, the formation of yellow fog is quite common-because of the thickness of the emulsions and the repeated use of partly exhausted fixing solutions.

The literature references in this field suggest other possible causes of dichroic fog, as well as various remedies for the problem. United States Patent No. 2,059,642, for instance, discloses the use of a mixture of soluble gold and mercury salts to prevent the formation of both grey and yellow fog. Similarly, in German Patent No. 635,605 (1936) and. in Photographische Korrespondenz, Band 72, Seite 148, the use of dihenyliodonium salts in emulsions and in the various processing baths is recommended for the prevention of this f0 Treatmfint with a bath of sodium sulfite and potassium cyanide has been suggested as a means of removing the yel- (Cassels Cyclopaedia low fog after its formation These of Photography, 1912, Vol. I, page 266).

methods cannot be considered wholly satisfactory since they often cause fiat gradation, forma- Application August 5, 1939, erial No. 288,580

ticn of grey fog, lowered sensitivity, or other disadvantages.

One object of our invention is to provide a new class of fog inhibitors which tend to prevent the 5 formation of yellow fog in photographic materials without the difficulties and disadvantages of the prior art.

Another object is to provide anti-yellow fog emulsion or in a surface or substratum layer without a noticeable decrease in the sensitivity of the emulsion.

,A further object is to provide new yellow fog inhibitors'which may be incorporated in the developing bath itself or in a separate processing bath.

Still further objects and advantages will appear from the following specification.

We have foimd that the above objects are accomplished by the use of phosphonium iodides and the related arsonium and antimonium compounds as well as the addition products or salts of the abovecompounds with various metal and alkyl iodides, as yellow fog inhibitors.

These compounds all contain the quaternary grouping wherein Y is phosphorus, arsenic, or antimiony,

. and I represents iodine. Although we do not wish to limit ourselves to any particular theory, it is our belief based on experience that the essential feature responsible for the excellent results produced by these compounds is the penitavalent Y grouping, of which one valence is 40 ftaken up by an iodine atom. Thus it is imwherein Y is phosphorus, arsenic, or antimony, as above, and wherein the substitutes R1, R2, R3 and R4 may besubstituted or unsubstituted allql,

agents which may be included in a photographic methyl-tn (3 nitropheriyl) arsonium iodide alkyia-aryl phosphonium-, arsonium-, and antimonium iodides such as methyl-triphenyl-phosphonium iodide, ethyl-triphenyl-phosphonium iodide, allyl-triphenyl-phosphonium iodide, trimethyl-phenyl phosphonium iodide, methyl-diethyl-phenyl-phosphonium iodide, methyl-tri-ptolyl phosphonium iodide HaC methyi-t'riphenyl-arsonium iodide, ethyl-triphenyl-arsonium iodide, allyl-triphenyi arsonium iodide, trimethyl-phenyl arsonium iodide, methyldiethyl-phenyl-arsonium iodide, methyi-t ri-ptolyl arsonium iodide, methy1-t'ri-(3-hydroxyphenyl) arsonium iodide OH on on methy1-tri-(3-aminophenyl) arsonium iodide, 05 al lyl-iribiphenyl arsonium iodide CHzCH=CH1 methyl-diphenyi-a-naphthyl arsonium iodide iodomethyl-tripheiiyl arsonium iodide cxm I .\I

and methylene-bis-tri-pheny1-phosphonium iodide alkyl-cycloalkyl-aryl phosphonium-, arsonium-,

and antimonium iodides, such as methyl-cyclohexyl-diphenyl arsonium iodide aryl phosphonium-, arsonium-, and antimoniuni iodides, such as tetraphenyl-arsonium iodide; aralkyl phosphonium-, arsonium-, and antimonium iodides, such as tetrabenzyl-phosphonium iodidecHl-P and tetrabenzyl arsonium iodide; aryl-araikyi I phosphonium-, arsonium-, and antimonium iodides, such as triphenyl-benzyi phosphonium iodide and triphenyi benzyl arsonium iodide; heterocyclie phosphonium-, arsonium-,-and antimonium iodides. such as ethyl-phenyltetramethylene-phosphonium iodide ethyl-phenyl-pentamethylene-phosphonium 10- 'dide CH2CH: C P-CRHi CHr-CHa I ethyl phenyl-tetramethylene-arsonium iodide, dimethyl-pentamethylene-phosphonium iodide.

CHr-CH:

CH: P-CHa CHr-CH: I

and methyl-phenyl-QO diphenylaresonium iodide and finally, addition products or salts of any of the above compounds with various metal and alkyl iodides, for example with bismuth iodide, and mercuric iodide.

Typical examples of such addition product are:

In order that those skilled in the art may better understand the nature and scope of this invention, the following specific examples are given without any intention of limiting the invention thereto.

Example 1 To 500 g. of a light sensitive gelatino-silver halide emulsion which normally shows yellow fog, melted at 40 0., are added from 10 to 20 mg. of methyl-triphenyl-arsonium iodide. The mixture is coated on a suitable support, chilled, and dried in the customary manner. The emulsion thus treated is free from yellow fog.

Example 2 The methyl-triphenyl-arsonium iodde of the preceding example may be applied to the emulsionby including it in a surface coating. In such a case the amount used should be so chosen that the same concentration of arsonium iodide per unit area of coated film based on relative thickness of surface and emulsion coatings, is obtained as in Example 1. Thus, if the surface coating is one-tenth the thickness of the emulsion coating, approximately ten times as much methyltriphenyl-arsonium iodide, or from 100 to 200 mgr., is added to 500 g. of surface coating solu.. tion. The film having a surface coating thus treated is free from yellow fog.

Example 3 To one liter of a common developer solution,-

such as any standard metol-hydroquinone for-- Example 4 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 C., are added from 10 to 20 mg. of tetraphenyl arsonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The emulsion thus treated is free from yellow fog.

Example 5 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 0., are added from to mg. of allyl-triphenylphosphonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The emulsion thus treated is free from yellow fog.

Example 7 To 500 g. of a light sensitive gelatino-silver halide emulsion as in Example 1, melted at 40 0., are added from 10 to 20 mg. of methyl-phenyl- 0.0-diphenyl arsonium iodide. The mixture is coated on a suitable support, chilled and dried in the usual way. The emulsion thus treated is free from yellow fog.

The quantities of the compounds used may, of

course, be varied slightly to suit the particular conditions involved.

since the presence of these new compounds tends to prevent yellow fog whether they are incorporated directly into the emulsion, added to a separate surface or substratum layer, added to the developing bath, or used in a. separate processing bath, we have used the term photographic material in the appended claims in a broad sense as including each of these possible applications.

We claim: 1. A photographic material containing as a yellow fog inhibitor for silver halide emulsions an organic compound containing the grouping wherein Y is a pentavalent atom selected from the group consisting of phosphorus, arsenic, and

antimony and wherein the dangling valences are supplied by organic radicles.

2. A photographic material containing as a yellow fog inhibitor for silver halide emulsions an organic compound having the grouping As I wherein the dangling valences aresupplied by orgame radicles. a

3. A photographic material containing as a yellow fog inhibitor for silver halide emulsions an organic compound corresponding to the formula wherein Y is a pentavalent atom selected from the group consisting of phosphorus, arsenic, and antimony and wherein the dangling valences are supplied by organic radicles.

4. A photographic material containing as a yellow fog inhibitor for silver halide emulsions a substance corresponding to the formula R3 R4 wherein Y is a pentavalent atom selected from the group consisting of phosphorus, arsenic, and antimony,

Y j a is a heterocyclic group, and R3 and R4 are members selected from the group consisting of alkyl,

cycloalkyl, aryl, aralkyl, and heterocyclic groups.

5. A photographic material containing as a yellow i'og inhibitor for silver halide emulsions a substance corresponding to the formula Rr-AS-I R: 4 wherein is a heterocyclic-group, and R3 and R4 are mem- 6. A photographic material containing as a yellow tog inhibitor for silver halide emulsions a substance corresponding to the formula substance corresponding to the formula wherein R1, R2 and R3 represent aryl groups. and R4 represents an alkyl group.

8. A photographic material containing methyltriphenyl-arsonium iodide as a yellow fog inhibitor for silver halide emulsions.

9. A light sensitive photographic gelatino-silver halide emulsion containing from 10 to 20 mg. of methyl-triphenyl-arsonium iodide per 500 g. of emulsion, as a yellow i'og inhibitor.

10. A photographic material containing allyltriphenyl-arsonium iodide as a yellowfog inhibitor for silver halide emulsions.

11. A light sensitive photographic gelatinosilver halideemulsion containing from 10 to 20 mg. 0! allyl-triphenyl-a'rsonium iodide per 506 g. of emulsion, as a yellow tog inhibitor.

- FRITZ DERSCH.

NEWTON HEIMBACH. 

